Diversity of the DNA Replication System in the Archaea Domain

Table 1

DNA replication proteins and features in the domains Bacteria, Eukaryota, and the two major phyla of the Archaea domain. Modified from [43].

DNA replication stage	Process	Bacteria	Eukaryota	Archaea
				Crenarchaeota	Euryarchaeota
Preinitiation	Origin of replication	Single	Multiple	Multiple	Single^a
	Origin recognition	DnaA	ORC complex (ORC 1-6)	Orc1/Cdc6	Orc1/Cdc6^b
Initiation	DNA unwinding (Helicase)	DnaB	MCM complex (MCM 2-7)	MCM complex	MCM complex
	DNA unwinding (Accessory proteins)	DnaC	Cdc6	GINS23/GINS15	GINS15^c
			Cdt1
			GINS complex (Sld5, Psf1-3)	RecJ homolog?	RecJ homolog?
			Cdc45
	Primer synthesis	DnaG	Pol 𝛼/primase complex	DNA primase (PriSL)/DnaG^d	DNA primase (PriSL)
Elongation	DNA synthesis (polymerase)	Pol III (Family C DNA polymerase)	Pol𝛿, and Pol𝜀 (Family B DNA polymerase)	Family B DNA polymerase	Family D DNA polymerase^e
	DNA synthesis (Processivity factors)	𝛾-complex (clamp loader)	RFC (clamp loader)	RFC (clamp loader)	RFC (clamp loader)
		𝛽-clamp (clamp)	PCNA (clamp)	PCNA (clamp)	PCNA (clamp)
Maturation	Maturation (Okazaki fragment processing)	Pol I (family A DNA polymerase)	Fen1/Dna2	Fen1	Fen1
		RNase H	RNase H	RNase H	RNase H
		DNA ligase	DNA ligase	DNA ligase	DNA ligase

aException, the order Halobacteriales.
^bNot known for members of the Euryarchaeota orders Methanococcales and Methanopyrales.
^cGINS23 has been founded only in the order Thermococcales of the Euryarchaeota.
^dSulfolobus solfataricus did show primase activity in vitro.
^eFamily B DNA polymerase is also essential in Halobacterium. Because its function has not been clearly elucidated, it might also play a role in replication in this and closely related organisms.